Catalyst for wax isomerate yield enhancement by oxygenate pretreatment

ABSTRACT

A dewaxing catalyst is selectively activated by treatment with an oxygenate. Selective activation is accomplished by treated the dewaxing catalyst with a carrier feed containing oxygenate. The selectively activated dewaxing catalyst when used to dewax waxy hydrocarbons results in improved yield of isomerate at equivalent pour point over a dewaxing catalyst which has not been oxygenate treated.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application claims benefit of U.S. Provisional PatentApplication Ser. No. 60/416,867 filed Oct. 8, 2002.

FIELD OF THE INVENTION

This invention relates to a catalyst for a wax dewaxing process. Moreparticularly, dewaxing catalyst is prepared by treatment with anoxygenate. The catalyst can be used in the dewaxing of lubricant oilfractions containing waxy hydrocarbons to improve isomerate yield andquality.

BACKGROUND OF THE INVENTION

Historically, lubricant oil basestocks were prepared by a solventextraction process in which a cut from a vacuum distillation unit issolvent extracted to produce a raffinate rich in paraffins and anextract rich in aromatics. The raffinate was then solvent dewaxed toaddress basestock quality issues such as pour point. The ability of thesolvent dewaxing process to meet increased demands placed on basestockquality is limited since improvements in properties such as pour pointcame at the expense of basestock yield. The solvent dewaxing process isdesigned to separate wax from base oil thereby eliminating the highestVI components of the waxy feed. Thus in order to achieve the target pourpoint, high VI components are removed thereby lowering the yield.

An alternative method for preparing lubricant oil basestocks iscatalytic dewaxing. Catalytic dewaxing may be accomplished by twodewaxing mechanisms: hydrocracking or hydroisomerization. The dewaxingcatalysts which function by hydrocracking generally result in basestockyields which are comparable to or lower than solvent dewaxing. Dewaxingcatalysts with an isomerization function can convert wax in feed toisomerate boosting yield and VI over solvent dewaxing to the same targetpour point. Dewaxing catalysts which function by hydroisomerization takelong chain waxy paraffins and isomerize them to branched chain specieshaving desirable low temperature and volatility properties. Under actualoperating conditions, it is not expected that a dewaxing catalyst willfunction exclusively by either mode of dewaxing.

Dewaxing catalysts with a hydroisomerization function are generallyintolerant of heteroatom contaminants, and typically employ ahydrotreating step before dewaxing in order to remove heteroatomcontaminants from the feed as such contaminants result in acceleratedcatalyst deactivation.

Although dewaxing catalysts with an isomerization function are wellknown in the art, there is still a need for catalysts, which result inbetter yields and product qualities by minimizing hydrocracking.

SUMMARY OF THE INVENTION

It has been discovered that the performance of dewaxing catalysts can beimproved by the addition of oxygenates. Accordingly, the presentinvention relates to a process for selectively activating a dewaxingcatalyst for the catalytic dewaxing of a waxy hydrocarbon feed whichcomprises: contacting the dewaxing catalyst with a carrier feedcontaining at least one oxygenate at a temperature of from 20 to 400°C., a hydrogen pressure of from 101 to 20786 kPa.

A further embodiment relates to a process for selectively activating adewaxing catalyst for the catalytic dewaxing of a wax containinghydrocarbon feed which comprises: contacting the dewaxing catalyst whichcontains at least one molecular sieve containing at least one 10 or 12channel with a carrier feed containing at least about 100 wppm ofoxygenate, measured as oxygen, at a temperature of from 20 to 400° C.and a hydrogen pressure of from 101 to 20786 kPa.

Another embodiment relates to a process for selectively activating adewaxing catalyst for the catalytic dewaxing of a wax containinghydrocarbon feed which comprises: contacting the dewaxing catalyst whichcontains at least one molecular sieve containing at least one 10 or 12channel with a carrier feed containing at least about 100 wppm, measuredas oxygen, of an oxygenate which is at least one alcohol, carboxylicacid, ester, aldehyde, ketone or ether at a temperature of from 20 to400° C. and a hydrogen pressure of from 101 to 20786 kPa.

Still another embodiment relates to a process for selectively activatinga dewaxing catalyst for the catalytic dewaxing of a wax containinghydrocarbon feed which comprises: contacting the dewaxing catalyst whichcontains at least one molecular sieve containing at least one 10 or 12channel with a carrier feed containing at least about 100 wppm, measuredas oxygen of an oxygenate which is water at a temperature of from 20 to400° C. and a hydrogen pressure of from 101 to 20786 kPa.

The catalyst for the dewaxing of wax-containing feeds is selectivelyactivated by oxygenate treatment and the selectively activated dewaxingcatalyst when used in a dewaxing process results in product with atleast one of improved yield, viscosity, low temperature properties andVI compared to a non-activated catalyst.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is a graph showing a comparison of the effect of oxygenatetreatment vs. no oxygenate on a hydrotreated slack wax.

DETAILED DESCRIPTION OF THE INVENTION

Feedstocks

The feedstock used in the process of the invention are wax-containingfeeds that boil in the lubricating oil range, typically having a 10%distillation point greater than 650° F. (343° C.), measured by ASTM D 86or ASTM 2887, and are derived from mineral or synthetic sources. The waxcontent of the feedstock is at least about 15 wt. %, based on feedstockand can range up to 100 wt. % wax. The wax content of a feed may bedetermined by nuclear magnetic resonance spectroscopy (ASTM D5292), bycorrelative ndM methods (ASTM D3238) or by solvent means (ASTM D3235).The waxy feeds may be derived from a number of sources such as oilsderived from solvent refining processes such as raffinates, partiallysolvent dewaxed oils, deasphalted oils, distillates, vacuum gas oils,coker gas oils, slack waxes, foots oils and the like, andFischer-Tropsch waxes. Preferred feeds are slack waxes andFischer-Tropsch waxes. Slack waxes are typically derived fromhydrocarbon feeds by solvent or propane dewaxing. Slack waxes containsome residual oil and are typically deoiled. Foots oils are derived fromdeoiled slack waxes. Fischer-Tropsch waxes are prepared by theFischer-Tropsch synthetic process such as that based on iron containingcatalysts as well as other Groups 8, 9 or 10 metal sulfide catalysts foruse in carbon monoxide hydrogenation.

Feedstocks may have high contents of nitrogen- and sulfur-containingcontaminants. Mineral based feedstocks may contain from 0 up to 0.2 wt.% of nitrogen, based on feed and from 0 up to 3.0 wt. % of sulfur, basedon feed can be processed in the present process. The minimum sulfurcontent of synthetic feedstocks based on Fischer-Tropsch waxes preparedusing iron or other Groups 8, 9 or 10 metal sulfide based catalysts isabout 0.5 ppmw, based on feed. Feeds having a high wax content typicallyhave high viscosity indexes of up to 200 or more. Sulfur and nitrogencontents may be measured by standard ASTM methods D5453 and D4629,respectively.

Feedstock Hydroprocessing

Feedstocks having high contents of nitrogen- and sulfur-containingcontaminants are preferably hydroprocessed prior to dewaxing.Hydroprocessing may be by hydrotreating or hydrocracking.

For hydrotreating, the catalysts are those effective for hydrotreatingsuch as catalysts containing Group 6 metals (based on the IUPAC PeriodicTable format having Groups from 1 to 18), Groups 8–10 metals, andmixtures thereof. Preferred metals include nickel, tungsten, molybdenum,cobalt and mixtures thereof. These metals or mixtures of metals aretypically present as oxides or sulfides on refractory metal oxidesupports. The mixture of metals may also be present as bulk metalcatalysts wherein the amount of metal is 30 wt. % or greater, based oncatalyst. Suitable metal oxide supports include oxides such as silica,alumina, silica-aluminas or titania, preferably alumina. Preferredaluminas are porous aluminas such as gamma or eta. The amount of metals,either individually or in mixtures, ranges from about 0.5 to 35 wt. %,based on the catalyst. In the case of preferred mixtures of groups 9–10metals with group 6 metals, the groups 9–10 metals are present inamounts of from 0.5 to 5 wt. %, based on catalyst and the group 6 metalsare present in amounts of from 5 to 30 wt. %. The amounts of metals maybe measured by atomic absorption spectroscopy, inductively coupledplasma-atomic emission spectrometry or other methods specified by ASTMfor individual metals.

For hydrocracking, the catalyst may be any catalyst used forhydrocracking. Such catalysts typically employ an acidic, large poresize zeolite within the porous support material with an added metalhydrogenation/dehydrogenation function. The acidic functionality in thehydrocracking catalyst is provided either by a large pore, amorphousmaterial such as alumina, silica-alumina or silica or by a large poresize crystalline material, preferably a large pore size aluminosilicatezeolite such as zeolite X, Y, ZSM-3, ZSM-18, ZSM-20 or zeolite beta. Thezeolites may be used in various cationic and other forms, preferablyforms of higher stability so as to resist degradation and consequentloss of acidic functionality under the influence of the hydrothermalconditions encountered during the hydrocracking. Thus, forms of enhancedstability such as the rare earth exchanged large pore zeolites, e.g.,REX and REY are preferred, as well as the so-called ultra stable zeoliteY (USY) and high silica zeolites such as dealuminized Y or dealuminizedmordenite. Hydrotreating and hydrocracking catalysts are commerciallyavailable from catalyst manufacturers.

The hydroprocessing catalysts may include a binder such as silica,silica/alumina or alumina or other metal oxides e.g. magnesia, titania,and the ratio of binder to zeolite will typically vary from 10:90 to90:10, more commonly from about 30:70 to about 70:30 (by weight).

Hydrotreating conditions include temperatures of from 150 to 400° C.,preferably 200 to 350° C., a hydrogen partial pressure of from 1480 to29786 kPa (200 to 3000 psig), preferably 2859 to 13891 kPa (400 to 2000psig), a space velocity of from 0.1 to 10 LHSV, preferably 0.1 to 5LHSV, and a hydrogen to feed ratio of from 89 to 1780 m³/m³ (500 to10000 scf/B), preferably 178 to 890 m³/m³.

Hydrocracking conditions include temperatures of from 300 to 480° C.,preferably 315 to 425° C., a hydrogen partial pressure of from 6996 to20786 kPa (1000 to 3000 psig), preferably 10443 to 17338 kPa (1500 to2500 psig), a space velocity of from 0.1 to 10 LHSV, preferably 0.5 to 5LHSV, and a hydrogen to feed ratio of from 178 to 1780 m³/m³ (1000 to10000 Scf/B), preferably 356 to 1780 m³/m³ (2000 to 10,000 Scf/B).

Hydrotreating or hydrocracking converts sulfur- and nitrogen-containingcontaminants to gaseous species such as hydrogen sulfide and ammonia.Since nitrogen-containing contaminants are typically the mostundesirable from the standpoint of maintaining dewaxing catalystactivity, conditions are such as to reduce nitrogen-containing speciesto acceptable levels with regard to maintaining catalyst activity.Hydroprocessing conditions which are sufficient to reduce theconcentration of nitrogen-containing contaminants to acceptable levelswill reduce oxygen-containing species to essentially zero.

Gaseous sulfur- and nitrogen-containing contaminants such as hydrogensulfide and ammonia are preferably separated from the hydroprocessedfeed prior to dewaxing by stripping or other separation techniques wellknown in the art for separating gases from liquids.

Dewaxing Selectivity

The present process for the catalytic dewaxing of waxy feeds utilizes acatalyst that has been activated by contacting the catalyst with anoxygenate. A preferred dewaxing catalyst is one whose mode of dewaxingis by isomerizing wax molecules to isomerates with boiling points in thelube range.

The dewaxing catalyst may be either crystalline or amorphous.Crystalline materials are molecular sieves that contain at least one 10or 12 ring channel and may be based on aluminosilicates (zeolites), ormay be based on aluminophosphates. Zeolites used for oxygenate treatmentmay contain at least one 10 or 12 channel. Examples of such zeolitesinclude ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57,ferrierite, EU-1, NU-87, ITQ-13, and MCM-71. Examples ofaluminophosphates containing at least one 10-ring channel includeECR-42, SAPO-11 and SAPO-41. Examples of molecular sieves containing 12ring channels include zeolite beta, ZSM-12, MCM-68 SAPO-5, SAPO-31,MAPO-36, ZSM-18, mordenite, faujasite and offretite. It should be notedthat a dewaxing catalyst such as ZSM-5 can have altered dewaxingproperties by adjusting catalyst properties, such as acidity, metaldispersion and catalyst particle size as noted in U.S. Pat. No.6,294,077. The molecular sieves are described in U.S. Pat. Nos.5,246,566, 5,282,958, 4,975,177, 4,397,827, 4,585,747, 5,075,269,6,303,534 and 4,440,871. MCM-68 is described in U.S. Pat. No. 6,310,265.MCM-71 and ITQ-13 are described in PCT published applications WO 0242207and WO 0078677. Preferred catalysts include ZSM-48, ZSM-22 and ZSM-23.Especially preferred is ZSM-48. As used herein, ZSM-48 includes EU-2,EU-11 and ZBM-30 which are structurally equivalent to ZSM-48. Themolecular sieves are preferably in the hydrogen form. Reduction canoccur in situ during the dewaxing step itself or can occur ex situ inanother vessel.

Amorphous dewaxing catalysts include alumina, fluorided alumina,silica-alumina, fluorided silica-alumina and silica-alumina doped withGroup 3 metals. Such catalysts are described for example in U.S. Pat.Nos. 4,900,707 and 6,383,366.

The dewaxing catalysts are bifunctional, i.e., they are loaded with ametal hydrogenation component, which is at least one Group 6 metal, atleast one Group 8–10 metal, or mixtures thereof. Preferred metals areGroups 9–10 metals. Especially preferred are Groups 9–10 noble metalssuch as Pt, Pd or mixtures thereof (based on the IUPAC Periodic Tableformat having Groups from 1 to 18). These metals are loaded at the rateof 0.1 to 30 wt. %, based on catalyst. Catalyst preparation and metalloading methods are described for example in U.S. Pat. No. 6,294,077,and include for example ion exchange and impregnation using decomposablemetal salts. Metal dispersion techniques and catalyst particle sizecontrol are described in U.S. Pat. No. 5,282,958. Catalysts with smallparticle size and well dispersed metal are preferred.

The molecular sieves are typically composited with binder materials thatare resistant to high temperatures and may be employed under dewaxingconditions to form a finished dewaxing catalyst or may be binderless(self-bound). The binder materials are usually inorganic oxides such assilica, alumina, silica-aluminas, binary combinations of silicas withother metal oxides such as titania, magnesia, thoria, zirconia and thelike and tertiary combinations of these oxides such as silica-alumina-thoria and silica-alumina magnesia. The amount of molecular sieve inthe finished dewaxing catalyst is from 10 to 100, preferably 35 to 100wt. %, based on catalyst. Such catalysts are formed by methods suchspray drying, extrusion and the like. The dewaxing catalyst may be usedin the sulfided or unsulfided form, and is preferably in the sulfidedform.

Dewaxing conditions include temperatures of from 250–400° C., preferably275 to 350° C., pressures of from 791 to 20786 kPa (100 to 3000 psig),preferably 1480 to 17339 kPa (200 to 2500 psig), liquid hourly spacevelocities of from 0.1 to 10 hr⁻¹, preferably 0.1 to 5 hr⁻¹ and hydrogentreat gas rates from 45 to 1780 m³/m³ (250 to 10000 scf/B), preferably89 to 890 m³/m³ (500 to 5000 scf/B).

Oxygenates used to selectively activate the dewaxing catalyst areorganic, oxygen-containing compounds (organo-oxygenates) which formwater under hydrodewaxing conditions. Oxygenates include carboxylicacids, alcohols including polyols, esters, aldehydes, ethers, ketonesand mixtures thereof, or an inorganic oxygenate which is water.Preferred oxygenates are alcohols, esters, ethers and carboxylic acids,especially alcohols. The organo moieties contain at least 1 carbon atomand may range up to oxygen contained in oxidized hydrocarbon feeds inthe lube boiling range (343° C.+as measured by ASTM D 86 or ASTM 2887).

The feed used to selectively activate (selectivate) the catalystcontains at least about 100 wppm, measured as oxygen, of at least oneoxygenate, preferably at least about 400 wppm, measured as oxygen, of atleast one oxygenate. Amounts of oxygenates greater than 10000 wppm maybe used if desired as such amounts will not adversely affect thedewaxing process or products. The total oxygen content of an oxygenatecan be measured by instrumental methods such as neutron activationanalysis which may be combined with high resolution proton nuclearmagnetic resonance, gas chromatography with oxygen flame ionizationdetector, gas chromatography-mass spectrometry (GC-MS) or fouriertransform infrared spectroscopy. Neutron activation analysis ispreferred for low concentrations of oxygenates. Oxygenate contents offeeds (as oxygenate) may be determined by proton nuclear magneticresonance or by GC-MS.

Various methods have been proposed for measuring the selectivity ofdewaxing catalysts. In one method described in J. Catalysis, 1984, 86,24–31, a feedstock is catalytically dewaxed over the zeolite whoseselectivity is determined at various reaction severities to achievedifferent product pour points. The conversion required to achieve agiven degree of dewaxing may then be compared with a reference catalystsuch as ZSM-5 to determine relative selectivity. In U.S. Pat. No.5,282,958, selectivity is measured for a given molecular sieve having adefined crystallite size and pore diameter by measuring theisomerization of n-hexadecane under a given set of test conditions.

In the present invention, selectivity for a given catalyst is defined asthe fractional amount of lube boiling range isomerate formed at thetarget pour point from the wax component of the feed. The improvement inselectivity as a result of oxygenate treatment for a given dewaxingcatalyst is to isomerize at least 4 relative % more of the wax componentinto lube boiling range isomerate at the pour point target, preferablymore than 6 relative %, most preferably more than 10 relative %.

The selectivity improvement for any give dewaxing catalyst may becalculated as illustrated in the hypothetical example given in thefollowing chart showing isomerate yield improvement at equivalent pourpoint for dewaxing a waxy feed. Catalyst A and Catalyst B (which isCatalyst A treated with oxygenate). The yield for the example isobtained by adjusting if necessary dewaxing conditions of temperatureand space velocity to achieve equivalent pour point.

Catalyst A Catalyst B (untreated) (oxygenate treated) Wax content offeed 90.0% 90.0% Yield of isomerate 61.0 wt. % 72.0 wt. % at target pourIsomerate selectivity 56.7* 68.9* Selectivity improvement  1.215**Relative selectivity 21.5%*** improvement % *Calculation: [61.0 − (100 −90)]/90 = 56.7 [72.0 − (100 − 90)]/90 = 68.9 **68.9/56.7 = 1.215; noimprovement is 56.7/56.7 = 1.0 ***(1.215 − 1.000) × 100 = 21.5%

For any given catalyst, isomerate yield should improve with increasingwax content of the feed. Thus feeds with higher wax contents, e.g.,greater than 40 wt. %, based on feed, are preferred.

Hydrofinishing

Following the dewaxing step, it is preferred to hydrofinish the productresulting from dewaxing in order to adjust product qualities to desiredspecifications. Hydrofinishing is a form of mild hydrotreating directedto saturating any lube range olefins and residual aromatics as well asto removing any remaining heteroatoms and color bodies. The postdewaxing hydrofinishing is usually carried out in cascade with thedewaxing step. Generally the hydrofinishing will be carried out attemperatures from about 150° C. to 350° C., preferably 180° C. to 250°C. Total pressures are typically from 2859 to 20786 kPa (about 400 to3000 psig). Liquid hourly space velocity is typically from 0.1 to 5 LHSV(hr⁻¹), preferably 0.5 to 3 hr⁻¹ and hydrogen treat gas rates of from44.5 to 1780 m³/m³ (250 to 10000 scf/B).

Hydrofinishing catalysts are those containing Group 6 metals (based onthe IUPAC Periodic Table format having Groups from 1 to 18), Groups 8–10metals, and mixtures thereof. Preferred metals include at least onenoble metal having a strong hydrogenation function, especially platinum,palladium and mixtures thereof. The mixture of metals may also bepresent as bulk metal catalysts wherein the amount of metal is 30 wt. %or greater based on catalyst. Suitable metal oxide supports include lowacidic oxides such as silica, alumina, silica-aluminas or titania,preferably alumina. The preferred hydrofinishing catalysts for aromaticssaturation will comprise at least one metal having relatively stronghydrogenation function on a porous support. Typical support materialsinclude amorphous or crystalline oxide materials such as alumina,silica, and silica-alumina. The metal content of the catalyst is oftenas high as about 20 weight percent for non-noble metals. Noble metalsare usually present in amounts no greater than about 1 wt. %. Apreferred hydrofinishing catalyst contains MCM-41 whose preparation anduse for hydrogenation is described in U.S. Pat. Nos. 5,098,684,5,227,353, 5,573,657 and 5,264,641.

Control of the reaction parameters of the hydrofinishing step offers auseful way of varying the stability of the products. The hydrofinishingcatalyst together with temperatures of about 150–350° C. (446°–572° F.)will minimize aromatics. They will also provide products having goodoxidative stability, UV light stability, and thermal stability. Spacevelocity in the hydrofinisher also offers a potential for aromaticssaturation control with the lower space velocities effecting greateraromatics saturation.

Catalyst Preparation and Process Description

Since normal hydrocarbon feedstocks derived from petroleum containamounts of sulfur and nitrogen that are detrimental to dewaxingcatalysts, it is preferred that such feedstocks are hydrotreated and/orhydrocracked prior to dewaxing. Thus the feedstocks to the presentcatalytic dewaxing process that contain unacceptable levels of sulfurand nitrogen contaminants are preferably hydroprocessed and subsequentlystripped to remove gaseous sulfur- and nitrogen-containing contaminantssuch as hydrogen sulfide and ammonia. If hydrocracking is the mode ofhydroprocessing, the hydrocracked product may be both stripped andfractionated to isolate specific cuts for dewaxing. The hydroprocessedfeedstocks are then sent to the dewaxing step.

The catalysts used in the catalytic dewaxing step are usually purchasedfrom a catalyst manufacturer. The user has the option of metal-loadingthe catalyst or purchasing the catalyst in the metal-loaded form. Asnoted previously, metal loading can be accomplished by impregnating thedewaxing catalyst with a decomposable metal salt such as an amine salt,e.g., platinum tetramine complex followed by heating. Sulfiding can beaccomplished by treating the metal loaded catalyst with a sulfidingmixture such as hydrogen/hydrogen sulfide or other sulfiding agent, orby contacting the catalyst with hydrogen and a feedstock spiked with asulfiding agent or by using a feedstock containing organo sulfurcompounds.

In order to selectively activate the dewaxing catalyst, the oxygenate ormixture of oxygenates may be added directly to the hydrocarbon feed tobe dewaxed. Alternatively, the dewaxing catalyst can be selectivelyactivated and the activated catalyst used in the dewaxing process. Inthe former process, a hydrocarbon feed containing at least about 100wppm, measured as oxygen, of at least one oxygenate is contacted withthe dewaxing catalyst under dewaxing conditions. Alternatively, thedewaxing catalyst can be selectively activated prior to use in thedewaxing process which activation may be separate from the dewaxingprocess itself. In this case, the dewaxing catalyst is heated at atemperature of from 120 to 400° C. and a hydrogen pressure of from 101to 20786 kPa (0 to 3000 psig) in the presence of a feed containing atleast about 100 wppm, measured as oxygen, of at least one oxygenate. Thefeed may be the same or different from the hydrocarbon feed to bedewaxed. Thus the feed may either be a carrier feed or the hydrocarbonfeed to be dewaxed. If the feed is a carrier feed, it is preferred thatthe carrier be a hydrocarbon such as product resulting from the presentcatalytic dewaxing process. As noted previously, the dewaxing catalystmay be used in the sulfided or unsulfided form and may be reduced.

Catalyst preparation and subsequent dewaxing can be accomplished in asingle reactor or in separate reactors. In a preferred embodiment, anoble metal loaded ZSM-48 dewaxing catalyst is placed in a reactor andhydrogen and a carrier feedstock containing sulfiding agent added to thereactor. It is preferred that the carrier feedstock be similar to abasestock cut expected as a final product, e.g., a 100N oil. Thecatalyst is reduced, sulfided or both reduced and sulfided. The reducedand/or sulfided catalyst can then be selectively activated by contactingwith a carrier containing at least one oxygenate. The carrier can beeither the feedstock to be dewaxed or some other hydrocarbon feedstocksuch as the carrier used to sulfide the catalyst.

Once the catalyst has been selectively activated with oxygenate(s), thefeedstock to be dewaxed is added to the reactor and dewaxing takes placeunder conditions defined above. Further oxygenate treatment may be addedas needed to maintain catalyst activity.

The product from catalytic dewaxing may be sent to hydrofinishing in aseparate reactor without any intervening disengagement. Direct cascadefrom dewaxer to hydrofinisher is preferred thus avoiding the expenseinvolved in an additional stripping step. Hydrofinishing is done in thepresence of hydrogen and a hydrofinishing catalyst. The hydrofinishingreaction conditions are noted hereinbefore. Hydrofinishing is useful toremove color bodies, enhance stability and improve toxicologicalproperties.

The hydrofinished product is then fractionated to isolate desiredlubricant products. The individual cuts of lubricants products areattractive as basestocks for meeting Group II and Group IIIrequirements. These Group classifications are those used by the AmericanPetroleum Institute (API). API Group II basestocks have a saturatescontent of 90 wt. % or greater, a sulfur content of not more than 0.03wt. % and a VI greater than 80 but less than 120. API Group IIIbasestocks have the same requirements as Group II basestocks except thatthe VI is greater than 120.

The following non-limiting examples will serve to illustrate the subjectinvention.

EXAMPLE 1

This example demonstrates slack wax isomerates yield credit sustained byZSM-48 catalyst selectivation using an oxygenate contained feedstock.The selectivation was carried out on a dried and reduced 0.6% Pt/ZSM-48bound with 35 wt. % alumina. The reference commercial ZSM-48 catalyst,0.6% Pt/ZSM-48/35 wt. % alumina in metal oxide form, was dried at 180°C. under 200 psig flowing nitrogen pressure for 3 hours. The catalystwas then reduced at 260° C. under 200 psig flowing hydrogen for 4 hoursto produce the dried and reduced catalyst (Cat-A). Temperature was thenreduced to 150° C. and hydrotreated 150N slack wax (table 1) was cutinto the unit.

ZSM-48 selectivation (Cat-B) was performed on a reduced catalyst (Cat-A)by processing an oxidized hydrotreated 150N slack wax containing between1000 and 3000 ppm O, as measured by Neutron Activation Analysis. Theselectivation was carried out at 332° C. under 1000 psig hydrogenpressure to produce Cat-B.

Four 316 stainless steel, ⅜″ diameter reactors with appropriate highpressure connectors were each charged with 8 cc of catalyst material tobe evaluated and 2 cc inert. The catalyst loaded reactors are immersedin a fluid bed, constant temperature sand-bath equipped with electricalheaters for temperature control. Appropriate mechanical connections wereinstalled to allow reactor operation at nominal pressure of 1000 psig(6.89 MPa) and nominal drying, reduction and test temperatures from 150°C. to 350° C.

Under steady state conditions liquid feed (hydrotreated 150 N slack wax)and gaseous high purity hydrogen (>99 vol. % H₂) are pumped over thefixed catalyst bed. Liquid and gaseous product are subsequentlydepressurized and sampled periodically. Aliquots of liquid product andliquid feed are analyzed for composition and quality.

Operating conditions were set to 332° C., 1.0 h⁻¹ Liquid Hourly SpaceVelocity (LHSV), and 1000 psig Hydrogen. The hydrotreated 150N slack waxliquid feed is described in Table 1.

Catalyst isomerate selectivity is assessed by calculating cracking.Cracking is calculated measuring gas and liquid effluents composition(370° C. minus) by GC and GCD (gas chromatographic distillation by ASTM2887) respectively, compared to hydrotreated 150N slack wax composition.Catalyst selectivity is determined by comparing yield of isomerate (370°C. plus) at equivalent pour. Pour points are determined by standard ASTMtest (D 97). The branched chain properties of isomerate was checkedusing NMR (nuclear magnetic resonance, particularly carbon 13 NMR).Isomerate quality such as viscosity and viscosity index was alsomeasured or calculated using standard ASTM tests (D445-94 and D2270-91)using a Houillon Automated Viscometer with a repeatability of 0.5%.

TABLE 1 Hydrotreated 150 N Slack Wax Composition Grade 150 N Sulfur(wppm) <2 Viscosity @ 100° C. (cSt)  3.601 Wax content (Wt. %) 95.6 Oilin wax (Wt. %)  4.6

TABLE 2 Cat-B Cat-A Reduced + [O] Treatment Reduced treated Days on Oil58 29 Temperature (′C) 332 332 370 + ° C. Yield (wt. %) 61.9 73.9Selectivity Improvement (%) Base +21 370 + ° C. Isomerate K. Viscosity @12.380 13.341 40° C. (cSt) 370 + ° C. Isomerate K. Viscosity @ 3.2623.501 100° C. (cSt) 370 + ° C. Isomerate Viscosity Index 137 148 370 + °C. Isomerate Pour Point (° C.) −20 −16

Data reported in table 2 show about a 10 wt. % yield credit (adjusted tothe same pour point) for the oxygenate selectivated catalyst. The errorlimits for yield and pour points are ±1 and ±3, respectively. Thecorrection for yield based on pour point is 0.55% for each degree C.change in pour point. Furthermore, product quality is also improved withabout a 10 VI improvement. The enhanced product quality can also be seenin the VI properties (148) in comparison to viscosity at 100° C. (3.5cSt). This feature of high VI at viscosity is indicative of theunusually high quality of the present products.

Wax isomerate selectivity is defined as:

${Selectivity} = \frac{{370{^\circ}\mspace{14mu}{C.{+ {yield}}}\mspace{11mu}(\%)} - {{Feed}\mspace{14mu}{oil}\mspace{14mu}{content}\mspace{14mu}(\%)}}{{Feed}\mspace{14mu}{Wax}\mspace{14mu}{content}\mspace{11mu}(\%)}$Selectivity Improvement is Defined as:

${{Selectivity}\mspace{20mu}{Improvement}} = \frac{{Selectivated}\mspace{14mu}{Catalyst}\mspace{14mu}{Selectivity}}{{Base}\mspace{14mu}{Catalyst}\mspace{14mu}{Selectivity}}$Calculation Example from Ex. 1

${{Selectivity}\mspace{20mu}{Improvement}} = {\frac{\left( {73.9 - 4.6} \right)/95.4}{\left( {61.9 - 4.6} \right)/95.4} = {\frac{0.726}{0.600} = {1.21\mspace{14mu}{or}\mspace{14mu} 21\%\mspace{14mu}{over}\mspace{14mu}{base}\mspace{14mu}{case}}}}$

EXAMPLE 2

This example compares isomerate selectivity of ex-situ sulfided (Cat-C)and in-situ sulfided (Cat-D) ZSM-48 to that of the reduced catalyst(Cat-A). This example also demonstrates yield advantage by oxygenatetreat of the ex-situ sulfided catalyst (Cat-E).

All catalysts were dried following the same procedure described inexample 1 prior to any treatment.

-   (a) Cat-C was pre-sulfided ex-situ by using a 400 ppm H₂S containing    hydrogen treat gas. Cat-C was loaded, dried and wetted with 150N    isomerate prior to processing hydrotreated 150N slack wax.-   (b) Cat-D was dried under nitrogen, then sulfided in-situ in the    reactor unit at 100 psig pressure and 200° C. for 48 hours using a    spiked isomerate containing 400 ppm sulfur as dimethyl-disulfide.-   (c) Cat-E was prepared in-situ in the reactor by treating the    pre-sulfided (Cat-C) with a spiked isomerate containing 1000 ppm    oxygen as n-decanol. The selectivation was carried out at 100 psig    pressure, 200° C. for 48 hours.

TABLE 3 Cat-E Cat-C Cat-D Cat-C Cat-A Ex-situ In-situ with [O] TreatmentReduced sulfided sulfided treat Days on Oil 58 8 8 8 Temperature (° C.)332 329 329 329 370 + ° C. Yield (wt. %) 61.9 61.9 61.0 73.7 SelectivityImprovement (%) Base 0 −1.5 +20.5 370 + ° C. Isomerate K. 13.28 12.78512.859 12.858 Viscosity @40° C. (cSt) 370 + ° C. Isomerate K. 3.2623.371 3.354 3.446 Viscosity @100° C. (cSt) 370 + ° C. Isomerate 137 143138 153 Viscosity Index 370 + ° C. Isomerate Pour −20 −19 −20 −17 Point(° C.)

Data reported in table 3 show activity and selectivity equivalencybetween ex-situ (Cat-C) and in-situ (Cat-D) sulfided catalysts.Furthermore, no yield advantage is observed over the lined-out reducedcatalyst (Cat-A). This example also shows that oxygenate selectivationof the ex-situ sulfided catalyst (Cat-E) produces a more selectivecatalyst having a 10 wt. % yield credit over the untreated catalyst(Cat-C).

EXAMPLE 3

This example shows the impact on selectivity by treatment with otherpolar compound such as nitrogen.

Cat-F was prepared in-situ by treating the pre-sulfided (Cat-C) with aspiked isomerate containing 20 ppm nitrogen as n-butylamine. Thecatalyst treatment with n-butylamine was carried out at 100 psigpressure, 200° C. for 48 hours.

TABLE 4 Cat-E Cat-F Cat-C Cat-C Cat-C Ex-situ with with Treatmentsulfided [O] treat [N] treat Days on Oil 8 8 8 Temperature (′C) 329 329329 370 + ° C. Yield (wt. %) 61.9 73.7 52.7 Selectivity Improvement (%)Base +20.5 −16 370 + ° C. Isomerate K. Viscosity @ 12.785 12.858 12.94840° C. (cSt) 370 + ° C. Isomerate K. Viscosity @ 3.371 3.446 3.390 100°C. (cSt) 370 + ° C. Isomerate Viscosity Index 143 153 141 370 + ° C.Isomerate Pour Point (° C.) −19 −17 −17

Data reported in table 4 demonstrate that treating the ex-situ sulfidedZSM-48 catalyst with a nitrogen compound results in a selectivity debit.This demonstrates the uniqueness of oxygenate over other polar compoundssuch as nitrogen compounds.

EXAMPLE 4

This example demonstrates the impact of higher temperature operation onselectivity on a selectivated catalyst. This example also demonstratesthat selectivation is reversible after a higher temperature operation aswell as the possibility to re-selectivated in-situ.

The ex-situ sulfided catalyst (Cat-C) was loaded and dried according tothe procedure described in example 1.

As shown in the Figure:

-   Stage 1, the catalyst was lined-out with an oxygenate free    hydrotreated 150N slack wax.-   Stage 2, the catalyst was then treated with the oxidized    hydrotreated 150N slack wax feedstock described in example 1    containing between 1000 and 3000 ppm oxygen (as oxygenate).    After Stage 2, the unit was washed using a medicinal grade white oil    to remove all traces of polars and aromatics. The catalyst    temperature was then increased to 350° C. under white oil at 1000    psig pressure and maintained at 350° C. for 36 hours. After the 36    hours hold, the temperature was reduced to the operating temperature    of 328° C., this operation was also conducted under white oil.-   Stage 3, after the higher temperature treatment, was run for 10 days    using the same oxygenate free hydrotreated 150N slack wax used in    stage 1.    At the end of stage 3, the catalyst was exposed to the oxidized    hydrotreated 150N slack wax feedstock described in example 1    containing between 1000 and 3000 ppm oxygenate, at 328° C. for 3    days.-   Stage 4, after the higher temperature treatment, was run for 10 days    using the same oxygenate free hydrotreated 150N slack wax used in    stage 1.

TABLE 5 Stage 2 Stage 3 Stage 4 Stage 1 Stage 1 Stage 2 Stage 3 Ex-situafter [O] after High after [O] Treatment sulfided treat Temp. treat Dayson Oil 8 14 38 49 Temperature (° C.) 329 325 328 328 370 + ° C. Yield(wt. %) 61.9 73.0 67.7 72.7 Selectivity Base +19 +10 +19 Improvement (%)370 + ° C. Isomerate K. 12.785 13.798 13.695 12.814 Viscosity @40° C.(cSt) 370 + ° C. Isomerate K. 3.371 3.571 3.515 3.393 Viscosity @100° C.(cSt) 370 + ° C. Isomerate 143 147 141 145 Viscosity Index 370 + ° C.Isomerate Pour −19 −19 −23 −19 Point (° C.) 370 + ° C. Isomerate 143 147141 145 Viscosity Index 370 + ° C. Isomerate Pour −19 −19 −23 −19 Point(° C.)

Data in table 5 and the Figure demonstrate:

-   a partial loss of the yield credit after higher temperature    treatment (Stage 3 versus Stage 2)-   that ZSM-48 can be “re-selectivated” in-situ after processing an    oxygenated containing feedstock    (Stage 4 versus Stage 3).

EXAMPLE 5

This Example demonstrates that the yield benefit from an oxygenatetreatment can also be achieved with an amorphous dewaxing catalyst.

A 600N slack wax was hydrotreated and then exposed to air while stillhot, and therefore subject to oxidation. A clean feed was produced in anintegrated unit where the hydrotreated slack wax was directly fed to thehydrodewaxing catalyst without being exposed to hot air or moisture. Thehydrodewaxing catalyst was an amorphous catalyst, 0.9 wt. % Pt on a 1.1wt. % fluorided alumina.

The results are shown in Table 6.

TABLE 6 Clean Feed Oxidized Feed 370° C. + yield (%) 69 73.3 (GCD*) KV@100° C. 5.78 5.78 VI 135 137 *GCD = gas chromatographic distillation

The data in Table 6 show that an amorphous dewaxing catalyst hasimproved yield when dewaxing occurs in the presence of feed containingoxygenates.

1. A process for selectively activating a dewaxing catalyst for thecatalytic dewaxing of a waxy hydrocarbon feed which comprises:contacting the dewaxing catalyst which is ZSM-48 in the hydrogen form onan alumina or alumina-containing binder with a carrier feed containingabout 100 wppm to 10,000 wppm measured as oxygen of at least oneoxygenate at a temperature of from 120 to 400° C., a hydrogen pressureof from 101 to 20786 kPa, provided that the mode of dewaxing is byisomerizing waxy molecules and the selectivity of the dewaxing catalystis improved by isomerizing at least 4 relative % more of the waxcomponent of the waxy molecules in the hydrocarbon feed into lubeisomerate.
 2. The process of claim 1 wherein the oxygenate is at leastone alcohol, carboxylic acid, ester, aldehyde, ketone or ether.
 3. Theprocess of claim 1 wherein the oxygenate is water.
 4. The process ofclaim 1 wherein the carrier feed is the wax containing hydrocarbon feed.5. The process of claim 1 wherein the dewaxing catalyst is sulfided,reduced, or sulfided and reduced.
 6. The process of claim 1 wherein thedewaxing catalyst bears a metal hydrogenation component.
 7. The processof claim 6 wherein the metal hydrogenation component is at least oneGroup 9 or 10 noble metal.
 8. A process for selectively activating adewaxing catalyst for the catalytic dewaxing of a wax containinghydrocarbon feed which comprises: contacting the dewaxing catalyst whichis ZSM-48 in the hydrogen form on an alumina or alumina-containingbinder, said ZSM-48 bearing at least one metal hydrogenatin componentwith a carrier feed containing at least about 100 wppm to 10,000 wppm ofoxygenate, measured as oxygen, at a temperature of from 120 to 400° C.and a hydrogen pressure of from 101 to 20786 kPa, provided that the modeof dewaxing is by isomerizing waxy molecules and the selectivity of thedewaxing catalyst is improved by isomerizing at least 4 relative % moreof the wax into lube isomerate.
 9. The process of claim 8 wherein theoxygenate is at least one alcohol, carboxylic acid, ester, aldehyde,ketone or ether.
 10. The process of claim 8 wherein the oxygenate iswater.
 11. The process of claim 8 wherein the carrier feed is the waxcontaining hydrocarbon feed.
 12. The process of claim 8 wherein thedewaxing catalyst is sulfided, reduced, or sulfided and reduced.
 13. Aprocess for selectively activating a dewaxing catalyst for catalyticdewaxing of a wax containing hydrocarbon feed which comprises:contacting the dewaxing catalyst which is ZSM-48 in the hydrogen form onan alumina or alumina-containing binder, said ZSM-48 bearing at leastone group 9 or group 10 noble metal, and containing at least one 10 or12 channel with a cater feed containing at least about 100 wppm to10,000 wppm, measured as oxygen, of an oxygenate which is at least onealcohol, carboxylic acid, ester, aldehyde, ketone or ether at atemperature of from 120 to 400° C. and a hydrogen pressure of from 101to 20786 kPa, provided that the mode of dewaxing is by isomerizing waxymolecules and the selectivity of the dewaxing catalyst is improved byisomerizing at least 4 relative % more of the wax into lube isomerate.14. The process of claim 11 wherein the carrier feed is the waxcontaining hydrocarbon feed.
 15. The process of claim 13 wherein thedewaxing catalyst is sulfided, reduced, or sulfided and reduced.
 16. Aprocess for selectively activating a ZSM-48 catalyst for the catalyticdewaxing of a wax containing hydrocarbon feed which comprises:contacting ZSM-48 in the hydrogen form on an alumina oralumina-containing binder with a carrier feed containing at least about100 wppm to 10,000 wppm, measured as oxygen, of an oxygenate which is atleast one alcohol, carboxylic acid, ester, aldehye, ketone or ether at atemperature of from 120 to 400° C. and a hydrogen pressure of from 101to 20786 kPa, provided that the mode of dewaxing is by isomerizing waxymolecules and the selectivity of the ZSM-48 catalyst is improved byisomerizing at least 4 relative % more of the wax into lube isomerate.17. The process of claim 16 wherein the carrier feed is the waxcontaining hydrocarbon feed.
 18. The process of claim 16 wherein theZSM-48catalyst is sulfided, reduced, or sulfided and reduced.
 19. Theprocess of claim 16 wherein the ZSM-48catalyst bears a metalhydrogenation component.
 20. The process of claim 19 wherein the metalhydrogenation component is at least one Group 9 or 10 noble metal.
 21. Aprocess for selectively activating a dewaxing catalyst for the catalyticdewaxing of a wax containing hydrocarbon feed which comprises:contacting the dewaxing catalyst which is ZSM-48 in the hydrogen form onan alumina or alumina-containing binder with a carrier feed containingat least about 100 wppm to 10,000 wppm, measured as oxygen of anoxygenate which is water at a temperature of from 120 to 400° C. and ahydrogen pressure of from 101 to 20786 kPa, provided that the mode ofdewaxing is by isomerizing waxy molecules and the selectivity of thedewaxing catalyst is improved by isomerizing at least 4 relative % moreof wax component into lube isomerate.